Switchgear and similar electrical isolation equipment are highly regulated by industry standards (e.g., IEEE, ANSI, etc.). Among other things, these standards specify how much temperature may rise within a switchgear cabinet and the maximum allowable temperature. To comply with the temperature limitations, ventilation is used in certain switchgear to improve ambient air flow through the switchgear cabinet. For example, in smaller switchgear like the HVL/cb™ series of metal-enclosed switchgear from Schneider Electric USA, Inc., air vents may be provided on the front door of the cabinet near the bottom thereof and on the back cover of the cabinet near the top thereof to create cross flow ventilation through the cabinet.
The air vents, however, can cause the switchgear not to pass certain industry safety standards. For example, in order for switchgear to be considered arc resistant under industry standards, the switchgear cabinet must not allow arc blast to escape during an arc event, as the hot arc blast can cause significant damage to nearby equipment and personnel. Some air vents therefore include a vent cover that remains open under normal operating conditions, but immediately closes upon occurrence of an arc event to seal the switchgear cabinet and thereby contain the arc event within the cabinet.
To keep the vent cover open, existing air vents employ a spring or similar mechanical biasing mechanism that continuously pushes or otherwise maintains the vent cover in an open position. When an arc event occurs, the resulting pressure surge forces the vent cover into a closed position, compressing the spring or other mechanical biasing mechanism in the process. As the spring or biasing mechanism compresses, it pushes with progressively greater force against the vent cover in a direction opposite the compression. The increase in resistance from the spring or biasing mechanism can cause the vent cover not to close immediately and/or completely during an arc event, potentially allowing arc blast to escape from the cabinet and creating a safety hazard for nearby equipment and personnel.
Thus, a need exists for a more effective way to close air vents in the cabinets of switchgear and similar electrical isolation equipment.